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What is required for a pilot to fly in another country?
What is required for someone who holds a pilot certificate in one country to fly in another country? First, I'm wondering if there are any general rules that would apply to any such situation. Second, for the sake of a specific example, what would be required for someone who holds a private pilot certificate in the U.S. to fly an aircraft registered in the Philippines within the Philippines (assuming that the aircraft type is one for which the pilot is rated in the U.S.?)

A US pilot can fly over Canadian airspace and back into the US without any special requirements. e.g. Grosse Ile MI to Cleveland OH.

@SteveKuo Yes, the Chicago Convention protects that right for all countries party to it. That only applies if you're flying an airplane registered in your own country, though, IIRC.

For your specific example, Philippines Civil Aviation Regulations Part 2 (Personnel Licensing), section 2.2.4 covers "Validation and Conversion of Foreign Licenses and Ratings." It states that a holder of a license from a "Contracting State in accordance with ICAO Annex 1" (this includes the United States) is eligible for "validation" of their foreign license. The validation process involves presenting the appropriate documentation of your license, ratings and logbook. For more than just PPL privileges, you must also pass a "skill test" and demonstrate the required knowledge and ability. The conversion ("validation certificate") gives you the same ratings you had on your US license and is valid for 1 year.
The FAA has a very similar policy for foreign-to-US license conversion, covered in 14 CFR §61.75. As in the Philippines, the FAA does not require a skills test for private pilot privileges, but a written knowledge test is required for conversion of an instrument rating.
Another question here on ASE discusses conversion from EASA (Europe) to FAA (US).
Most other ICAO states recognize each other's licenses in a similar manner. In all cases you have to present your license and proof of experience, and in some cases pass a written test and/or checkride. I haven't look up the exact regulations for, say, EASA (Europe) or CAAC (China) but I'm sure they aren't far off from the examples above. In reality diplomatic considerations probably also come into play: a holder of an Iranian license would probably run into problems attempting to convert/validate their license in Israel, even though both are ICAO-contracting states, since they aren't on very good political terms to say the least. But this will likely be the exception rather than the rule.
(There are only 3 non-ICAO states: Dominica, Liechtenstein and Tuvalu.)

Thanks! Good answer. I did note, though, that it doesn't look like the skills test applies to a PPL only. It has a separate section for that in 2.2.4.1 (c). PPL/IR, CPL, ATP, etc. do require the skills test, though, per 2.2.4.1 (d). For PPL only, it just says you need to present your license and have a valid medical and that your validation is good for as long as your license and medical are valid.

@reirab You're right, thanks, will update accordingly.

Most countries other than the US also require a radio license. Not sure if it specifically applies in the case of the Philippines, but it is often the first step a US pilot needs to take in order to be eligible to fly elsewhere, regardless of the airplane's registration.

They would probably also require an aircraft, but admittedly I'm no expert

FWIW Sweden is one of the countries that requires a radio telephonist license.

Tuvalu and Dominica have since joined, leaving only Liechtenstein (which doesn't have an international airport).

It varies hugely depending on the country. Iceland simply allows the holder of an ICAO license to exercise the privileges of a PPL for up to 90 days with no additional tests or validation required aside from a current medical.
I did this myself a year ago, and was able to determine the requirements by simply emailing the ICAA, who responded promptly:

Foreign visitors in Iceland can use their valid and current ICAO pilot licence for three months for private VFR flights in Icelandic airspace in aeroplanes registered in Iceland. So as long you as licence is current and valid and you have sufficient privileges to fly the aeroplane in question. You can fly private VFR for three months in Icelandic airspace without having to validate your licence.

This is a difficult question to answer without country specifics, unfortunately.

War story time! Circa 1982. Landed in Managua, Nicaragua. They were not our friends back then, being communist and all. Some airport official wanted to see our pilot licenses only because the plane was U.S. military and they wanted to harass us. They knew that USAF pilots don't have pilot licenses. We don't get any FAA certification or ratings upon flight school graduation. Ironic.


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What happens to Cessna electric flaps that are moving when power is lost?
On final in a C182T you move the flap control arm from 20 to FULL, and when halfway there, the breaker pops (or BUS1 fails, a wire falls off, etc.)
Does the flap stay where it is, slide back to 20°, slide back to UP, or something else? Perhaps the question is “are the stops mechanically significant?”
Would the answer change if instead of blackout it was a brownout? I.e. the motor is still trying to run, but doesn’t have all of its normal oomph.

@quietflyer  Are you seriously suggesting that someone (who presuamably isn't a test pilot) deliberately disable their aircraft, while in the air?

Never mind, I suppose with fancy glass panels and what-not-all kinds of electronic engine systems, you probably don't want to do that.  No, I'm certainly not suggesting anything whatsoever.  He could stand outside the plane on the ground and have someone switch off the master while the flaps were in transit, maybe even while he applied gentle pressure on the moving flaps by hand.  If I were flying a more basic sort of a Cessna though, I certainly wouldn't consider switching off the master to be "disabling".

Stays where it is. The mechanism is a leadscrew and like most leadscrews it's "self-locking", which means that it's held in position by frictional forces whenever the motor isn't turning and it can't be back-driven even by substantial loads. The 20 degree (etc) "stops" are just reference positions for which aircraft performance and load limit data have been determined.

I would think if there are 2 motors, the stops also provide assurance both wings are in the same position.  You wouldn't want to, say, run both motors for 5 seconds and hope they move to the same position...

@Harper the flaps on both wings are joined by a mechanical linkage that ensures they always move together. There is only a single motor that drives both. Having separate motors and separate mechanisms per wing with no rigid linkage between wings would be quite a dangerous design unless extensive (& expensive) extra safety systems were incorporated to prevent asymmetric deployment. Such complications may make sense on a transport-category aircraft where the longer wingspan and cabin arrangement prohibits the simple approach, but they wouldn't make sense on a light GA aircraft.

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Is the ratio of HP to weight constant for identical air frames of different sizes? (See Scenario)
In my head it seems logical that there would be a proportion between engine HP and empty weight. For example, the Wright Flyer weighed around 600 LBS empty and had a 12 HP engine. If I were to make an exact 1/6 size scale replica out of the same materials that weighed 100 pounds and had a 2 HP engine, would that aircraft fly as well? Would the performance be exactly the same? Thanks in advance!!!
(Don't bother accounting for the pilot's weight.)

In an aircraft, engine power is used to overcome drag. Drag is related to weight, but not in an 1:1 ratio.
There are several types of drag:

Parasite drag: related to the surface area of the aircraft, incl. all the aircraft components that don't produce lift.
Lift induced drag: this is related to lift, which is related to weight.
Wave drag: we'll ignore this for low speeds.

(I'm simplifying things here)
Total drag depends on airspeed. like this:

When you scale an aircraft, things get more complicated. The weight scales with the volume of the aircraft. Your 1/6 scale aircraft won't weigh 1/6 of the original, but (1/6)^3.
Drag scales with surface area, so it'll be closer to (1/6)^2. I suspect lift scales with surface area as well.
So as your aircraft gets smaller, its weight drops faster than its lift, so the wing loading gets lower.
This also means the control surfaces become more effective, and the roll/pitch/yaw rates go up.
This means your takeoff and landing speeds become lower.
In practice, model aircraft fly at much lower speeds than their fullsize counterparts. So they're in a different part of the drag vs. speed graph shown above. This complicates the calculation of how much engine power you need for a model.
If you made a video recording of a full-size aircraft and sped it up, you'd get a decent approximation of what the scaled aircraft would look like.

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How much different are civilian and military aircraft autopilots?
The requirements for military and civil aircraft are pretty different, so this possibly applies to their autopilots. Are they different in the way they function or capabilities that they are programmed with?

I think you're question is too wide, since there are hundreds of different types, who could know them all?  On the military aircraft I have worked on, the autopilots did not have any special functions and, on some models, were the same as fitted to civilian aircraft.

What I mean is something general.. Like, a fighter jet is mostly at supersonic speeds and thus it is required to be faster.. Whereas, a civil autopilot has to control a greater number of equipments and is likely to get more time in case of some emergency.

An autopilot controls the flying controls - "civil autopilot has to control a greater number of equipments". What do you mean?  They all have the same control surfaces.  Do you understand that the autopilot does speed, heading, position and altitude?  It does not control everything on the aircraft..

@anshabhi fighter jets are rarely supersonic, super cruise withstanding, its much to inefficient to keep the burners lit and cruise above 1.0.

There is no civillian autopilot for an F-16, because there are no non-military F-16s. Ditto with the F-117 or or B-1 or B-2, so who knows what unique modes those autopilots have for their uniquely military missions (i.e. dropping bombs or low level terrain following). However, when the military aircraft has a non-military equivalent (KC-10/DC-10, KC-135/B707, C-40/T-43/B737, C-21/Learjet, T-44/C-12/KingAir, etc) then the autopilots are generally identical.
Any differences are more likely to be found in FMC software rather than in the Autopilot, and those differences would be very specific to each aircraft & its mission.

Caveat - only worked on 2 aircraft with terrain following and on both, the terrain following RADAR took over from the autopilot, overriding input commands to it.  The reason is simply that you cannot tell an autopilot to maintain 300 feet but please climb a bit to avoid the hills.  Bomb dropping was also controlled by systems other than the autopilot.  Never seen an auto pilot that does more than speed, height, heading, vertical speed etc,

@Simon. Good point... There is just no civillian analog to those sorts of things... Modes, interfaces, and the whole architecture are just different with those sorts of missions - no civil counterpart.

The autopilot in the super hornet is inferior to what you'd find in a typical Southwest flight.  It's got a heading hold, waypoint couple, baroalt hold and auto throttles, but none of them are linked together and all operate independently of each other.  There is no vertical speed hold, and no FMS to tie it all together.  The one thing it has is autotrim, but then again, so does the average Airbus.

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What is the maximum height for deploying a parachute?
i see a detachable plane cabin project .When an airplane crashes, the human toll is generally heavy. Based on this observation, Vladimir Tatarenko, a Ukrainian engineer who worked in particular for the Russian aeronautical manufacturer Irkut, have a idea:the pilots join the passengers, and the cabin is ejected from the rest of the plane. The landing is carried out smoothly thanks to a system of parachutes and floats. The inventor of the concept is very serious, he even filed a patent in 2014 and invested $ 50,000,he he is currently looking for investors.
This concept of ejectable aircraft cabin is not yet ready to arrive on the market. If two Ukrainian aeronautical universities are working on the development of a model, the engineer is currently on the hunt for investors. Eight years will be needed to develop its concept, which is estimated to cost nearly two billion dollars.
The additional cost generated to equip the aircraft is estimated by Vladimir Tatarenko at "a  few percent  " of the list price of an aircraft, but 95% of passengers would however be ready to pay for their plane ticket 15% more if their plane was equipped with an ejectable cabin . A system nonetheless of no help in the event of a bomb on board or a missile fire.
But I am not sure that this is achievable,because of weight,height...for the weight they claim  that it's possible with new ultra-light materials based on carbon, but which prove to be very expensive.The last limit concerns the flight phase during which the crashes take place. Between 2004 and 2013, out of all the crashes, 14% took place during takeoff and initial climb, and 47% took place during the final approach and landing. All these flight phases taking place between 0 and 1000m altitude, the opening of the parachutes may be too late to save the passengers.
what is the maximum height for deploying a parachute?
is it technically possible? knowing that Parachutes for aircraft already exist and are developed by several companies including Ballistic Recovery Systems (BRS) which has already saved 350 lives thanks to its system. The product consists of a parachute, stored under the fuselage and which deploys after activation of a joystick by the pilot. A sail of some 220m² then comes to deposit the entire device on the ground. This solution already equips several models from the manufacturers Cessna and Cirrus which can transport from 2 to 5 passengers.

https://brsaerospace.com/

Are you asking at what minimum altitude a chute can be deployed so that it fully opens/slows the object down? Or are you asking if chutes can open at cruising altitudes (35,000+ feet)?

@Ron Beyer Both

Related question: https://aviation.stackexchange.com/q/9243/520

Minus voters please explain what to improve in this question. Just hitting -1 is the same as wearing an ass for a hat.

Not a downvoter, but there doesn't seem to be a question here, so much as a promotion of a product.  Seems to be a solution in search of a problem; given that it would be of no help for CFIT, accidents on takeoff or landing, aircraft shot down by a SAM, or deliberately flown into a mountain or the Indian Ocean... I'm not seeing many cases where this contraption would be of use -- certainly not enough to justify the immense cost of incorporating it into production.  To say nothing of the risks that such a system would entail.

Changed my mind... "What do you think about this project" is the real question here, and it's CLEARLY in the realm of opinion-based. DV+VTC.

See, that was not so hard. And I have to say I agree with you @RalphJ

People must know....i am not for this project! I just want to talk about it so the -2....

...although I think this falls into the category of needs detail or clarity. Asks too many separate things.

Dv+vtc what do you want to say?

L'aviateur this is not a discussion forum, Stack Exchange is a Q&A site. Opinions are frowned upon, facts shall prevail.

Yeah you are right sorry i have edit somes things

I know you're not the one proposing this absurd concept but it is just such a dumb idea that I couldn't help but downvote... Sorry!

“What is the maximum height for deploying a parachute?” Probably somewhere in the neighborhood of 60,000 feet MSL. I have no citation for this opinion. Based on what I have seen and experienced, there will be some limiting factors that will not make a parachute effective beyond that. As a matter of fact, a better plan would be to fly the plane as long as possible to a lower altitude and speed before deploying a parachute above a safe landing zone. Or, (less ideally) you may deploy a drogue chute until you reach a lower altitude and speed before deploying the main chute.
One limiting factor is air density. Most jumpers who have parachuted higher than the 100 millibar pressure altitude (roughly 51806 feet or 15790.5 meters) have cited the same thing. There is a lack of directional stability and control due to not enough air resistance. A small drogue chute is necessary just to keep from tumbling uncontrollably. Deployment of a parachute in this state would be extremely dangerous. Even once you are stabilized, this same phenomenon might make it difficult to inflate a parachute once it has been deployed. Skydivers have a similar issue when their pilot chute is not thrown far enough away from their body during deployment. The pilot chute gets caught in the aerodynamic “burble” in the wake of their body.
A second limiting factor is speed. If you use a drogue chute to stabilize the free fall, it has to be large enough to produce sufficient drag to slow the falling object to a terminal velocity that the main chute can handle. Otherwise, you risk stressed seams, blown gore panels, snapped suspension/shroud lines, or the failure of the riser connection points. I’ve seen all but the riser failure on military airborne operations at speeds as low as 160-190 knots. I’ve seen the aftermath of even the riser failures on airborne drops of equipment at much lower speeds. And, if you increase the strength of the parachute used so that you can handle higher speeds, you would have to increase the parachute’s weight.
A third and maybe the most important limiting factor is safety. Deploying a parachute at a higher altitude may be of equal or greater danger than the underlying emergency. As a pilot, your number two concern has to be for the lives of your passengers. Your number one priority has to be for the lives of those on the ground, IMHO. If I had no other choice, I’d rather crash my plane in an open field than in a densely populated area. You give up more and more of that choice the higher you deploy the parachute.
I’ve seen experienced jumpers crash T10C and -1B parachutes into trees, buildings, power lines, etc. even at deployment altitudes under 2000 feet. I, myself have had an accidental deployment of my reserve chute when the retention pin broke upon exiting the aircraft at 17,000 feet. I was able to steer the ram-air canopy back to the dropzone. But, the deployment bag and pilot chute ended up drifting out of site.
The higher you deploy the parachute, the more likely you will be at the mercy of the winds. A rogue drogue or pilot chute may not cause too much damage. 350 pounds of soldier with gear may cause much more damage (especially to themselves). Even a 1380-2550 pound single engine GA aircraft may cause an acceptable level of damage. A fuselage for 100-400 people falling in a populated area will be catastrophic.
As for the minimum amount of altitude for safely deploying a parachute, I’ve always heard the rule of thumb from riggers and jumpmaster to be three times the length of the parachute itself.

Are you pilote? The conceptor suggest some rules for the security

@L'aviateur - Yes, and a former paratrooper and civilian skydiver. I’ve also flown LSA’s equipped with BRS chutes. Although the idea of a parachute on a much larger airplane is intriguing, there are many drawbacks to work out. Then, there is the original question of maximum altitude. Even a steerable canopy like the ones being used to recover some reusable civilian spacex booster rockets probably should not be fully deployed at extremely high altitudes.

Also, your cabin will become unpressurized shortly after being detached from the sources of bleed air (engines + APU) and the fuel tanks.  How long does this chute take to drift down from umpty thousand feet, compared to the supply of O2 in the PSU's?

Is there air in hight altitude ?....because parachute need air! And for the O2 it is possible to have a presurrized cabine...but weight....i thinks this project is a good idea but the disadvantages outweigh the advantages!

@L'aviateur - Yes, there is air. Please see my previously written answer above. I covered that. Approximately half of our atmosphere is below 18,000 feet. The atmospheric pressure at sea level is roughly 1000 mb. At 18k feet, it is 500 mb. At 35k feet, it is 250 mb. At 52k feet, it is 100 mb. Then, read the part about needing sufficient air resistance. Even at lower altitudes where there is air, canopy deployment is not guaranteed. As far as breathable air, some skydivers will jump as high as 20k while carrying no oxygen. You need oxygen on the aircraft for passengers above 15k by FAR 91.211.

Please vote my question up

@L'aviateur - Robert Alan Eustace made a jump at around 135k feet using a drogue chute to slow him to just over 800 mph.   https://en.wikipedia.org/wiki/Alan_Eustace.  He deployed his main chute much, much lower and slower.

Not for large passenger aircraft.  Single engine failure flies on.  2 engine failure?  I'd rather have a (shielded) 3rd engine, perhaps doubling as a very robust APU.  Probability of a major structural failure in a commercial aircraft is not high enough.  Both pilots incapacitated, same.  Saving people from a loss of control due to spatial disorientation or a spin, not in an airliner, but very good for GA aircraft.
Military or cargo transport, possibly, which would involve dropping an entire modular unit instead of pallets.  The application could be an emergency shelter or command post in a remote or natural disaster stricken area.
As early space capsules have shown, parachutes are workable from very high altitudes and great speeds (with drouge chutes).  There is no maximum altitude.
Detachable, interchangeable modules for cargo and passengers would certainly make a plane more versatile, but probably could more easily be slid off by opening one end, like a 747.  The attachments to the frame of the aircraft for 2 separate external units may be much weaker than one semi-monocoque fuselage.
Large helicopters such as the Sikorsky S-64 Skycrane utilize a similar concept of a flying frame/cargo module arrangement.  This idea may be best worked backwards from an application.

a fatal plane crash ratio for 2.54 million flights. Aviation Safety Network (ASN)

I like your Skycrane example. Although, the S-64 is more of a way of attaching an engine to a container box with a cockpit hanging off of the front. It does not need much structural support at its extremities. I am wondering how the designers of the OP’s project will account for structural support for the wings loaded with fuel and engines as well as the empennage. A box inside a box set up might be better. Alla Russian nesting planes. Otherwise they may have the same structural design issues convertible car engineers have with increased weight versus the coupe cars from which they’re derived.

Or, how about a variation of the Stratolaunch with a third, detachable fuselage. Just a thought.

@L'aviateur 1/2.54M yes, and in how many of such fatal accidents would this contraption be possibly useful? 1 of 5? 1 of 10? 1 of 100? See my point?

Maybe less...almost all accident are during land and take off

@L'aviateur - Your better option at any phase of flight is to continue to fly the aircraft all the way to the ground (and beyond if you make a safe landing). As long as you have some positive control of your flight. Given the option of pulling the deployment handle (not a joystick) of the BRS system on my rental aircraft, I would not unless I were in a non-recoverable spin. Or, if I lost a wing or empennage. The spin may be non-recoverable due to design limits, POH restrictions, or altitude. Or, it may be too well developed to recover. Any other reason, I probably should not have flown anyway.

@L'aviateur - Anecdotally, I know some pilots who do not remove the safety pin from the BRS deployment handle. They fear accidental deployment more than the extra few seconds it takes to remove the pin in an emergency. To each their own. Also, there is a greater risk to first responders when trying to extract pilot and passengers from a plane with an undeployed BRS chute due to the explosive ballistic (rocket) nature of the system.


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Reduction in Service Ceiling / Change in RVSM
I did some research and minimum vertical separation used to be 2000ft but it changed to 1000ft in 2002 and they want to change it to 500ft on american territory. Is this correct? Why they wouldn't change it to 500ft on European territory also ?
2nd question:if aviation is evolving yearly, then airspace is getting more and more crowded. there is Concorde who has retired but used to fly at 60.000ft for example, why instead of designing new aircraft to fly higher, they would reduce the service ceiling ? I heard that from an engineer but I don't find an explanation. Statistically, they are reducing the service ceiling. Can anyone give an opinion? example? Thanks.

It's a little unclear what you're asking. How are they "reducing the service ceiling"? If you're asking why they don't make airliners that fly at 60,000 feet there are numerous engineering challenges involved.

The way I understood it is that if an A320 service ceiling is 41000, they will soon or later make another aircraft that won't have higher service ceiling in fact it will have the same abilities (fuel consumption, speed etc) but will have lower service ceiling.

I haven't heard anything like that. The two latest large airliners to come out, Airbus A350 and Boeing 787 both have a ceiling of 43,000 ft. That's pretty much going to be the limit without going supersonic and there are several questions on the site addressing the additional problems of building supersonic airliners

You might want to split these into two separate questions. The second one is related to: Why are many jet aircraft designed to cruise around FL350-370?

1(a). Yes, in the US, below 18,000 feet and above 3,000 feet, airspace seperation is 500'.
3,000' and above to 18,000 feet:
IFR traffic, eastbound fly at odd thousands
VFR Traffic, eastbound fly at odd thousands + 500'
IFR traffic, westbound fly at even thousands
VFR traffic, westbound fly at even thousands + 500'
(I always figured that was because "east is even" would be too easy to remember.  JUst like Nav lights, red is in the left because "red on the right" would be too easy to remember. Red/Green is likely a carryover from boating tho.)
1(b), I don't know about Europe.
2 I believe service ceiling is more a factor of jet engine efficiency and aircraft drag.  Piston engine's need to be turbocharged or turbonormalized (make sea level power at altitude) to make the high teens need to make air denser for the engine to make power - if you can get up there, the drag drops a lot and you can go a lot faster.  Jets are big compressors in essence and can make all the dense air they need to burn jet fuel with.
Why don't more jet arcraft fly higher? Maybe it's not worth it drag reduction-wise, or time savings enroute-wise, to climb higher and then to descend back down.

Based on the title I believe the first part is talking about RVSM airspace above FL290, so the VFR altitudes wouldn't be relevant.

Thank you very much for your opinion. So basically this engineer means that engines are changing and speed is increasing therefore drag drops so the only limitationis would be something like in case of cabin depressurizing, it would be much easier to descent to 8000ft from FL320 than from FL420 in certain ammount of time depending on regulation or the oxygen supply. what do you think ?

Or down to FL140 even, plenty of air there (folks hike to the top of Pikes Peak in Colorado all the time, 14,110 feet).  I think will still want FL410 for long distance flights for low drag (from the aircraft body, not the engines) and things like ease of maneuvering around summer thunderstorms.

"East is even" would be too easy to remember, he said sarcastically.  For those of us who grew up in the western half of the US, knowing that people from the "East are Odd" was VERY easy to remember, so the mnemonic for that one DID make sense (at least to half of the population).  :-D

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How the fuel in the wings is managed in case of an engine failure?
Consider an aircraft has fuel tanks only in wings (No central tank).
Will the fuel for the respective engines will be consumed from the respective wings?
In case of a single engine failure, if the fuel is keep on consumed by the active engine, whereas not consumed in the inactive/damaged engine, will this affect the aerodynamic property of aircraft?

The fuel can be crossfed to the other engine

while not a duplicate, this question has some similarities https://aviation.stackexchange.com/questions/52805/what-could-the-fuel-pump-failure-have-been-that-my-flight-experienced/52807#52807

On 747-100/200 aircraft you can cause any engine to operate from fuel in any of the seven or nine tanks, except for the reserve tanks, which drain into their respective main tank. Thus, in case of an engine failure (or 3-engine ferry), it does require the flight engineer to stay awake to manage the fuel. If he doesn't stay awake and the captain notices the airplane is getting a little wing heavy on a side, it is usually sufficient to turn and, in a loud voice and with appropriate 4-letter words, wake the flight engineer.

That’s a pretty broad topic and depends on the aircraft in question and the fuel systems which it uses.
Large airplanes like jetliners have complex fuel management systems which feed fuel from the main tanks into feeder tanks which the engines can “drink” from.  The process is automated in modern aircraft - around the same time that the Flight Engineer went the way of the dinosaur - so little, if any, input from the crew is required in the process.
On smaller twins, say, for example, a Cessna 310, fuel is provided to the engines via a dedicated main fuel tank and optional aux tanks for each engine.  In the event of an engine failure, the pilot can select the ability to cross feed the good engine on the fuel system for the bad engine in order to prevent a fuel imbalance.

While a tank generally provides fuel to the engines on that wing, an engine can also use fuel from the tank on the opposite side, if the crossfeed valve is opened by the setting in the control panel. While the question itself may not be a duplicate, this answer likely explains enough.

14 CFR § 25.1001 Fuel jettisoning system.

(a) A fuel jettisoning system must be installed on each airplane unless it is shown that the airplane meets the climb requirements of §§ 25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprised of a takeoff, go-around, and landing at the airport of departure with the airplane configuration, speed, power, and thrust the same as that used in meeting the applicable takeoff, approach, and landing climb performance requirements of this part.

14 CFR § 25.121 Climb: One-engine-inoperative.

(d) Approach. In a configuration corresponding to the normal all-engines-operating procedure in which VSR for this configuration does not exceed 110 percent of the VSR for the related all-engines-operating landing configuration:
  (1) The steady gradient of climb may not be less than 2.1 percent for two-engine airplanes, 2.4 percent for three-engine airplanes, and 2.7 percent for four-engine airplanes, with -
  (i) The critical engine inoperative, the remaining engines at the go-around power or thrust setting;
  (ii) The maximum landing weight;
  (iii) A climb speed established in connection with normal landing procedures, but not exceeding 1.4 VSR; and
  (iv) Landing gear retracted.
  (2) The requirements of paragraph (d)(1) of this section must be met:
  (i) In non-icing conditions; and
  (ii) In icing conditions with the most critical of the approach ice accretion(s) defined in Appendices C and O of this part, as applicable, in accordance with § 25.21(g). The climb speed selected for non-icing conditions may be used if the climb speed for icing conditions, computed in accordance with paragraph (d)(1)(iii) of this section, does not exceed that for non-icing conditions by more than the greater of 3 knots CAS or 3 percent.

In short - in case of an engine failure, fuel may be dumped to achieve acceptable handling characteristics for approach.
Furthermore, I would add that based on many articles I've read about engine failure involving fire, it's not uncommon for nearly all fuel to be dumped before landing, to avoid a fireball on the ground. I will attempt to find some references for this.


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Are there any guidelines or regulations for seat legroom on airlines?
I am over 6' 2" and endured an extremely unpleasant 9-hour flight last year.  Shorter folk were just fine. Are there any guidelines or regulations for seat legroom on airlines?

Dave45, you lucky guy. I am 6'6", and flying in coach is simply becoming impossible.

I recall the fun and games when some fat guy (Kevin Smith?) was charged double or chucked off coz he couldn't fit in a standard seat.. what about tall guys?  What rights do paying customers have to be able to travel comfortably?  It seems the answer is "none". Unless you are a film director maybe?

@PeterKämpf Man, I feel sorry for you. I'm 6'1" and my knees already touch the seat in front of me on a lot of flights.

The short answer is no, beyond the need for an aircraft to satisfy the emergency evacuation requirements set by the FAA and other regulators. There must also be room for an approved seat cushion and seatbelts. So there is a point where a lack of legroom would impede evacuation to the extent that an aircraft couldn't pass the 90 second evacuation requirement, but there's generally no specific minimum legroom requirement.
The main exception is in the UK, which does have a form of minimum requirement (according to that link, the UK is the only country with one). The requirement is given as a different form of measurement from how airline seat pitch is normally defined, but the above link indicates that it basically translates to a 28-inch seat pitch. That's about as low as any airline goes, namely Spirit in the US. Most airlines draw the line at 30", with a few low cost carriers doing 29"

Nice answer; can you give an official link to FAA regulation? about seat width, is there anything similar in force anywhere?

@jj_p The first link in this answer is a link to the official FAA regulations. "14 CFR" stands for "Chapter 14 of the Code of Federal Regulations," which is the chapter pertaining to aviation and space, also known as the FARs (Federal Aviation Regulations.)


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What is this square hole for?
When waiting to depart Edinburgh today I noticed a square hole (looked to be something that can be opened and closed) on the rear of the right side of the aircraft.
Never seen it before and no idea what it's purpose is. Anyone know?
The opening is below and to the right of the rear door on the right hand side of the aircraft

(image source)

I was unable to upload the image directly. If someone is able to edit the post and upload the image from the link that would be great

To save others a web search, G-UZHG seems to be an A320-251N(SL).

Can you add a circle around the spot by any chance?

It serves as a place for which to insert a round peg

@quietflyer I got a chuckle out of that.

Cabin pressurization outflow valve.
Cabin pressure in an airliner is maintained by bleeding air from the engine compressors into the cabin, after conditioning (usually cooling and humidifying) it. Current designs are beginning to use separate air compressors for this.
In either case, the cabin pressure is regulated by controlling the difference between inflow, provided by the bleed or compressor, and outflow, which is a simple motor-controlled valve.
Generally the inflow is set to maximum and the outflow is varied, as this provides the maximum fresh air flow for the passengers.
See also:
How does the outflow valve work on a cabin pressurization system?
How does the cabin pressure controller work in a large commercial airliner?
How does the cabin pressure controller work in a large commercial airliner?
https://www.airspacemag.com/flight-today/how-things-work-cabin-pressure-2870604/
Can an aircraft re-pressurize at high altitude?

That's not an outflow valve. Outflow valves are normally on a bulkhead in the interior pressure hull, and dump into an unpressurized area like the tail cone or unpressurized equipment bay.   That's is more likely to be a dump valve for ground operation to ensure the fuse stays unpressurized with the packs running.

Yes but that little door is not an outflow valve. Outflow valves are regulating poppet valves.   Most airliners have some kind of way to bypass the normal pressurization outflow valves dump air overboard on the ground and I assume that's what that is.


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What is the difference between Jet Wash and Jet Blast?
I was reading about Wake Turbulence in Wikipedia and got to know about Jet Wash and Wing Vortex. According to Wikipedia, Jet Blast is the movement of air from the jet exhaust. Isn't this same as Jet Wash? What is the difference between the two?

Jet Blast is the force or wind generated behind a jet engine, particularly on or before takeoff when high/full power is set, but also when the aircraft is taxiing.

When an object moves through air (or some other medium, e.g. a spoon through nutella), air is disturbed. This disturbance or wake is known as wake turbulence. It can also be called jet wash.
The difference is that jet blast is only because of engines. Jet wash or prop wash or wake turbulence is because the airplane moves through air.
If Mr Kevin Fast runs at say 100 mph doing this (see picture below), you can notice significant wake turbulence, although the engines are off and there is no jet blast.

I can confirm that jet blast makes it difficult to stand, and also blows laptops away if you don't catch them. :)


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Can a F-35 shoot while hovering?
I know fictional aircraft are different than real ones but there is an F38 on Black Ops 2 (F35 based plane in 2025)
http://callofduty.wikia.com/wiki/FA38
It appears in a mission like this

Could a F35 shoot while hovering?

@jjack - It has a stealthy centerline gun pod with 220 rounds, more than the internal with 182 rounds. The pod isn't loaded when not needed. Gun pod test footage (first test, 120 round burst)

Please stop using the "fighter-jet" tag, it has been declared not-needed and it is being deleted.

@Federico Why ?

No, it cannot, at least there is no reason for it to do so...
A) The stick while in "hover mode" does not control the pitch/roll of the aircraft, but the forward/lateral position of the aircraft. This means that the aircraft can only shoot forward in a level attitude, it can't pitch up/down to hit a target.
B) When in "hover" mode, the landing gear are deployed and the weapons doors are closed. The F-35 is not particularly maneuverable while hovering (it isn't meant for combat, only for landing/take-off), so you are extremely vulnerable while hovering anyway (you can't open the doors to fire missiles, you can't pitch up/down to fire guns). Combat is not a design scenario for hover mode on this aircraft.
C) The F-35 use a tremendous amount of fuel while hovering, to the tune of about 1000lbs per minute. It only holds about 13,000lbs of fuel. You aren't going to spend a lot of time hovering.
D) It only holds 220 rounds of ammunition.
As for why your game character is so dumb, you'll have to ask the game developers that question.

@jjack - The Harrier is even less maneuverable in a hover, with ~4% excess thrust. The F-35B was designed with ~10% (LM was a bit overly conservative speccing the engine, which is understandable given the atrocious record of previous STOVL/VTOL fighter programs). During the initial competition, Boeing famously criticized LM's over-sized engine; LM in turn painted "Too Much Thrust" on one of its aircraft. If you're referring to VIFFing in the Harrier, all the pilot comments I've seen have basically said it was 'less than useful' in real combat.

Also, I think someone demoing the travel sim said something to the effect of  'selecting hover mode disables the weapons for safety.'

@jjack That is long discussed on the comments in the very link you provided. VIFF in air combat is probably a myth


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External Batteries
As a part of a project for a class we were tasked with trying to cut emissions/energy waste of airplanes. Now we've realized that running the apu on the ground at the gate and taxiing is a serious waste of energy and has high emissions. I was wondering if you guys had any other thoughts on inefficiencies on the airplanes and any ideas around backup power for the airplane anytime that is on the ground. This includes taxiing.
Our group was also looking at external batteries that can be attached and detached to the plane but was worried about such batteries existing.
I'm new here, but any information helps!

There are also already portable carts that have diesel generators attached (Called GPUs). These often have the fuel capacity to power the aircraft on the ground overnight and are most often used at remote bays. (Those bays that you can only assess by bus).
Otherwise, you essentially "Plug your airplane into the wall" and use city power to avoid use of the APU

You may consider editing the title to be more specific (there are many questions that can be asked about batteries, having a specific title help navigating through this website) and to transform it in a question (this is a Q&A website). It may also help you formulate a less broad question.

Don't forget that the electricity to charge those batteries needs to come from somewhere. That's going to involve burning something or damming something or splitting something or killing birds or something that someone is against...

At gate aircraft is usually hooked up to an external power source to reduce emission. This can be in the form of ground power cable like your power socket at home or ground power unit.
During taxi APU is not strictly needed as main engines would be already running and provide all the electricity or bleed air needed.
Lugging around a HUGE external batteries create its own problem. How to get the batteries back to gate after the plane take off? You use a vehicle (emission) to get them back? And when the batteries reach end of life you need an environmental friendly eay to dispose of it. Multuply that by number of airports and you can see the problem.

Some interesting questions to read:
What powers an aircraft prior to the APU being switched on?
What is the cable connected to a plane for?
Can airliners operate without an operating APU?


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Why is lift larger than thrust?
It's been a while since I tried to read a little about flight mechanics and aerodynamics, but I remember one question I had back then:
Is the thrust of a common passenger aircraft (A320, B737) greater than its lift-off weight and thus could it take off vertically?
A320:

Max take-off weight   73.5 (78) tonnes
Thrust range  98 (120) kN

73,5 tonnes = 73500 kg * 9.81 m/s^2 = 721035 N = 721 kN
If my calculations are correct, it could clearly not (a result like what one would expect intuitively)!
But how can the dynamic lift be larger than the weight using comparatively little thrust?
Rephrased: How can the dynamic lift be larger than the thrust?
Is there an invisible equivalent to gears at work here?

A complex math at work here but in simple form, thrust is used to generate forward movement. Movement of air above wings then create lift. Lift from wing then overcome weight for airplane to takeoff. Design of wings and angle of attack play more role than thrust. You can have tons of thrust but no lift with bad wing design and vice versa

Since trust serves to overcome drag, the basic question boils down to 'how can lift be higher than drag?'.

I know this question is old, but it just popped up on the recent activity list. So, one thought: I had a somewhat related question at Physics.SE: "What does a wing do that an engine can't?"

GLIDERS have lift with ZERO thrust.

@CharlesBretana The glider pushes itself with a gravitational component.

No it doesn't. The ONLY force acting on a glider is the aerodynamic forces acting on the surface of the aircraft, and (if you are analyzing the problem in the Accelerated frame of reference of the earth), the force of gravity, which is always straight down, normal (perpendicular) to the earth's surface, and can therefore not exert any horizontal or lateral force on the aircraft. The LIFT produced by a glider's wings is due to it's forward velocity through the air.

This question is seriously flawed and should not be answered.  Re : "But how can the dynamic lift be larger than the weight using comparatively little thrust? Rephrased: How can the dynamic lift be larger than the thrust?"  It is not correct to "rephrase" the statement in this way.  The two statements are in no way equivalent.  In a steady-state climb, lift is LESS than weight, but is (typically) LARGER than thrust.  For more, see https://aviation.stackexchange.com/a/56476/34686 .

Since the two "rephrasings" are not equivalent, we really have two completely separate questions here, which should be asked separately.

Oh, Charles. When the glider is pointing down it has a thrust component from gravity.  BTW to the closers of this question, could you please find one answer that says more than:  well, it just is?  Clue:  it may have something to do with the upper wing and Reynolds number.

Thrust is needed to overcome drag, and a good airplane design can create a lot of lift for little drag. In the case of an A-320, the lift-to-drag ratio is 18 in cruise (a little less during take-off), so to lift those 78 tons needs only 4.33 tons of thrust. All it needs is the right amount of forward speed, and the engines only need to maintain this speed.
Gliders are even more efficient, their L/D can approach 60. A glider of maybe 450 kg mass (= 4412 N weight) will create a drag force of only 74 N, admittedly at a much slower speed than an A-320.
To be more precise, in a climb the thrust will actually compensate a little of the weight, in addition to the drag, depending on the climb angle. The thrust needs to grow by weight $\cdot$ sin($\gamma$), where $\gamma$ is the flight path angle. If the A-320 had enough thrust to lift all its weight, it could take off vertically, flying in a nose-up, vertical attitude. Modern fighter aircraft do really have that much thrust installed.

This drawing shows a climbing aircraft. There are four forces at work:

Lift L (blue arrow)
Drag D (red arrow)
Thrust T (green arrow), and
Weight m$\cdot$g (black arrow)

For a trimmed state, the concatenated arrows should form a closed trapezoid (lightly shaded arrows). Note that both thrust and drag are drawn longer here in relation to weight and lift than they are in reality.
To answer the why part needs a few more lines. Lift is created by deflecting the airstream over the wings downwards. This change in momentum is lift, and creating it would be free of drag if the wing's span would be infinite and the air inviscid. In reality, flying causes these drag components:

Lift creation incurs a small backwards-pointing component which is biggest at slow speed and decreases with speed. To be precise: This drag component is proportional to the aircraft's span loading (weight divided by wingspan) and the inverse square of airspeed. It is called induced drag because it could be successfully calculated first with the same equations that describe electric induction.
Flying through air causes friction. This friction drag grows almost with the square of airspeed and is proportional to air density and surface area.
In inviscid flow, the sum of pressures around a body would just cancel out. In reality, the pressure on the forward-facing sections is normally higher than that on the aft-facing sections. This drag component is called pressure drag and is also proportional to the square of airspeed at the same angle of attack.

At the speed of best L/D the sum of 2 and 3 is equal to 1, and 2 and 3 are of the same magnitude for a well-designed airplane. High subsonic and supersonic flight adds a fourth component, called wave drag, and it's onset is the reason why the A-320 prefers to fly not much faster than Mach 0.78.

https://www.mathsisfun.com/definitions/trapezoid.html -- maybe "trapezium" for speakers of British English?

@quietflyer A bit attention to the colors would also add a lot of understanding. Note that the light arrows are shifted copies of the darker arrows, which of course all have labels.

@quietflyer I am shocked - shocked! - that you failed to spot the obvious mistake with the dash in "A-320". This completely invalidates the whole answer - don't you agree?

"Note that the light arrows are shifted copies of the darker arrows"- The way that part of the red drag arrow overlies the curve of the wing airfoil tends to give the illusion that it is shorter than it really is and creates the appearance of a big difference in length between it and the light red copy of it at the bottom of the trapezoid.  This was really the root of my confusion; my mistake. In fact in my comment I mis-identified what the light red copy was supposed to represent. I still think care should be taken to make sure the Lift vector (and its copy) is shorter than the Weight vector.

Peter's answer is very good, but to explain a little more of the 'why,' consider the forces that are at play. In order for a mass to not accelerate in a given direction, the sum of the forces acting on it in that direction must be zero (or the mass infinite, which brings about a whole new set of problems...) In the case of an aircraft that is cruising, there are 3 important categories of forces to consider: gravity, thrust, and the force of the aircraft hitting the air in which it's flying. The latter category is, of course, the most complicated one.
The sum of the forces applied to the aircraft by the air that it's running into can be modeled as 3 component forces which are all perpendicular to each other: the net sum of forces pushing the plane backwards (drag,) the net sum of the forces pushing the plane upwards (vertical lift,) and the net sum of the forces pushing the plane to the left or right (I'll call this horizontal lift.) When the plane is not turning, the horizontal lift is zero.
In order to maintain a given altitude, the vertical lift must be of equal magnitude to the weight of the airplane (the force applied to it by gravity). In order to maintain a given forward speed, the thrust must be of equal magnitude to the drag (assuming, for the sake of simplicity, that the thrust is pushing the aircraft straight forward.) So, the important thing to notice is that the thrust needs only to counter the backward component of the forces applied by air hitting the aircraft, not the total force applied by air hitting the aircraft. In a well-designed aircraft, the upward component of the force of air hitting the aircraft will be much larger than the backward component.

When the wing is moving horizontally, the air produces a force $F$ on the wing, and $F$ has two components, $L$ and $D$.  Because the angle of attack of the wing is generally much less than $45$ degrees, $D$ is also much smaller than $L$.  Since the thrust of the aircraft is only balanced with $D$.  Therefore, with a small thrust, a large force $L $ can be generated, $L$ can be used to balance the weight of the aircraft.

Is there an invisible equivalent to gears at work here?

Yes, the lifting areas of the wing (top and bottom) are much greater than the frontal drag area presented in the direction of flight.
Have a look at the lift vs angle of attack graphs posted in the answers to this question.
You will notice the large increase in lift reaching a maximum at around 11 degrees.  This lift comes from the top of the wing at very little expense to increased drag as a result of curving airflow and lower pressure above the wing.
At higher angles of attack, greater than stall, lift and drag (drag = thrust for constant speed) dutifully follow their linear relationship: at 45 degrees you do get lift, but with much higher drag.
Another item worth mentioning, in addition to area "gearing ratio" is the effect of the "boundary layer" attached to the aircraft, moving with it.  As long as it does not become excessively turbulent, it acts as a "grease", further reducing thrust requirements due to drag.

Re "Yes, the lifting areas of the wing (top and bottom) are much greater than the frontal drag area presented in the direction of flight." -- this seems a vast oversimplification.  If things were really this simple, it seem that manned flight would have been invented at least a few centuries earlier!

@quiet flyer. Well, they had some ideas about bird-like shapes, but propulsion was the issue for sustained manned flight.  With enough thrust even L/D "monstrosities" can fly.  Aviation followed the internal combustion engine and just as automobiles did, with a few steamers and electrics too.

Lift is greater than thrust because for a plane able to fly it can be demonstrated experimentally (in a wind tunnel) that Lift_constant > Drag_constant.
The formulas for lift and drag are:
1) Lift = Weight = Lift_constant x Density x Reference_surface x V^2
2) Drag = Thrust = Drag_constant x Density x Reference_surface x V^2
From 1 and 2 it follows that:
Lift = (Lift_constant / Drag_constant) x Thrust
If the plane is built in such a way that Lift_constant / Drag_constant > 1 then Lift > Thrust, otherwise it is not.

This answer could be improved by replacing "constant" with "coefficient".  Also by deleting the first sentence.  Also by specifying that the last two sentences apply only to linear, horizontal, constant-speed, steady-state flight.

This answer could also be improved by noting that an aircraft with a L/D ratio of less than 1 would be quite a monstrosity and definitely an oddball/ outlier case.


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How much oxygen do commercial airliners carry?
How much oxygen do commercial airliners carry? Is is enough for every seat to have a 20-30 minute supply, is it a percentage of total flight time (ie 10% of total flight time), or is there a compressor on board?
I would assume the goal of the pilots during depressurization would be to repressurize whether that be by simply lowering altitude or other means. Thus, I would assume (hope) there would be sufficient reserves of O2 to do one or the other.

The masks are connected to a chemical oxygen generator by a lanyard.  Pulling the mask pulls the lanyard, which pulls a pin from the generator and starts the reaction.  They typically last betweeen about 10 and 20 minutes, more than enough time to get down to 10,000 feet where additional oxygen is not required.
There is no need for a % of flight time since the crew will descend to a safe altitude then divert to the nearest suitable field.  Therefore, the only requirement is to last during the (emergency) descent.
You cannot "repressurise" since the cabin altitude will be the same as the external altitude.  The only thing to do is to increase the partial pressure of oxygen by descending.
It's worth mentioning that the flight crew each have their own, isolated supply from a bottle which lasts significantly longer.  This is so that they can continue to fly if there are fumes in the cockpit.  Cabin crew often have their own, smaller, portable bottles so that they can freely move about the cabin to assist the "self loading freight".
Many's a morning when I would arrive to work feeling, ahem, a little "under the weather" and nip into the cockpit for a couple of minutes on 100% oxygen.  Works wonders - and don't worry, they are topped up to full as part of the pre-flight service.

Cool. Would there ever be case where it would be unsafe to fly lower (such as over mountains)?

Yep, pray for clear skies ;)  15-20 minutes should be enough to fly away from the 10,000' and above threats.  But whatever, you got to get down before the oxygen supply runs out or your passengers start to croak.

Thanks, this kinda reminds me of my IP's response to why we dont fly out over the coast more during our cross country (TPA-BTR) he said, "I want to limit how far I need to swim" imply that we shouldnt go father than we could glide back in...

It's also worth noting that the flight crew's masks are pressurized (or can be, by flipping a switch) which allows them to clear smoke/fumes from the mask, as well as to continue breathing at altitudes where simply enriching the ambient air with oxygen would not be sufficient. Also cabin crewmembers get portable "walkabout" cylinders to enable them to attend to passengers who might have trouble with their masks.

@MatthewPeters: There are places, such as Tibet, where you would hit terrain before you get down to 10,000 feet, and getting to lower ground would take more time than the oxygen masks last. Airline flights generally avoid those places, for that reason.

@Henning, that's what I was thinking with my IP's response comment -that is do not fly over any terrain you cannot glide safely away from...

Just wondering, in the event of smoke or fumes in the cockpit/ cabin, is there a dump switch you can activate to depressurize the cabin and pump in outside air?  Decompression isn't that bad as long as the crew can remain conscious and perform the emergency descent.  What I'd be most concerned about is smoke inhalation from a lingering problem such as a fire.

Re: your comment about sipping on the oxygen - there was a crew I heard about that would bust the bottle-to-throttle rule, sometimes drinking in flight, then using the oxygen to sober up close to destination. They eventually caught them when their oxygen tanks kept having to be topped up every flight.

So what if I'm in the middle of the pacific ? Wouldn't it be impossible to reach any airport before the fuel ran out due to increased consumption inducted by lower altitude ?

@Antzi No, because you make sure you have enough fuel that that's not a problem. There are a few situations you have to have enough fuel for; one is the situation where you get out to the point where you're the absolute furthest from your diversion airports (around halfway across) and the plane depressurizes. You have to have enough fuel to proceed at standard post-depressurization cruise to an alternate. You don't just put the bare minimum fuel; you have enough to deal with contingencies.

@SHAF: That would probably be worth a separate question.

@RhinoDriver: The outflow valve can be manually controlled; this can, yes, be used to depressurise the cabin in flight if need be (by cranking the valve full open).  It can also be used to prevent the cabin from pressurising in the first place, either purposely (for instance, if someone found cracks in the pressure hull, necessitating an unpressurised ferry flight to the nearest heavy maintenance base for repairs) or accidentally.

They don't carry oxygen tanks for each passenger but instead use chemical oxygen generators that activate can provide at least 15 minutes of oxygen. They activate when the person pulls down the mask.
These 15 minutes is enough for an emergency descent to a safe altitude ~10k ft where there's enough oxygen in the air for people to breathe without needing the mask any more.

While some pressurized aircraft use oxygen generators as others have described, others use pressurized (up to 3000 psi) gaseous oxygen canisters. An engineer who designs such systems showed me how central oxygen systems work, but I believe there are smaller units (per seat group) on B787s and A350 XWBs.
They would carry at least 15 minutes of oxygen, but how long it lasts depends on how many people are using masks.

Welcome to aviation.se Gabe. Do you know how much oxygen is in those canisters, i.e. how long would they provide oxygen flow?

@DeltaLima: I can't find a reference for how much O2 they contain, but they would have 15-20 minutes worth. Unlike an oxygen generator that has a chemical reaction lasting for a fixed amount of time (15 min. usually), though, the duration of flow depends on how much is used.


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How do "tip jet" helicopters cancel the torque effect of the main rotor?

Some helicopters use "tip jet" on the rotor blades tips such as the McDonnell XH-20 Little Henry and Hiller YH-32 Hornet.
How do they cancel the rotor torque (often canceled by the tail rotor)?

There is a small amount of torque reaction, but it's in the opposite direction, with the rotor, and it's simply from friction drag of the hub bearings - the rotor is trying the pull the body around with it, however small.  In a hover in dead still air, bearing drag may be enough to cause a very slow yaw in the direction of the rotor's rotation, but there is usually enough air blowing past the vertical rudder surfaces just from downwash to cancel it out.  Of the designer can impart a passive compensating moment by tilting the vertical surfaces slightly.

What torque are you referring to?

Oh that just looks like too much fun...

This is a basic physics question, involving Newton's third law of motion  (For every action, there is an equal and opposite reaction.) When a centrally mounted engine applies force to turn the rotor, the equal and opposite reaction creates torque on the fuselage.  With a tip jet, the force is applied by the jet shooting its exhaust perpendicular to the blade, so the reaction is that the blade moves in the opposite direction.
So the answer is that tip jets don't CANCEL the torque, they simply don't create the torque in the first place.

Actually, they DO create torque, but in the opposite direction, due to friction within the bearings. Several orders of magnitude smaller than with a 'traditional' helicopter design.

@MikeBrockington yes, but more relevant than bearing friction is probably that the rotor downwash has a significant vorticity component, which will tend to swirl the fuselage with it.

@Mike Brockington: Sure, but since this is a physics-based answer, I'm assuming an ideal frictionless rotor bearing :-)

@jamesqf I understand that you want to talk about spherical chickens, but this forum is Aviation, not Physics, so the question remains of how does this design of helicopter control its direction - if it is facing North, and wants to fly South, how does it achieve this?

For the small amount of friction & downwash torque, would the tail perhaps have a control surface that tilts left and right? It would make sense for yaw control also.

@Mike Brockington: But that wasn't the question, was it?  The question was about how the rotor blade torque is canceled.  How tip-jet helicopters do directional control is an entirely different question.

@jamesqf  OK, let me rephrase then: This forum is Aviation, not Physics, so the question remains of how does the helicopter deal with the torque that DOES exist, (but in the opposite direction,) due to friction within the bearings?

@Mike Brockington: I can only say that  1) I wonder if the amount of torque from bearings is actually large enough to be significant; and 2) Since I don't happen to have a tip-jet helicopter to experiment with, I don't know how to come up with a reasonable answer.  Or indeed, how they would do directional control at all when in a hover or near-hover.

Speaking only for the model in the picture above, the answer to how the helicopter changes its direction is with a traditional tail rotor.

@Mike B: IDK about that.  Granted that it's not a great picture, but I can't see anything like a tail rotor on the boom that extends to the rear.

Are these still in production?

@MikeB in the above picture, if you look closely at the windscreen area, you can plainly see the image background was poorly edited out. if you follow that edit line to the upper tail you can see a small stub of the upper tail rotor blade over the lower striped blade. I have no idea why the sky/background was edited out. It is a very small rotor, but it is there.

Think of the aircraft engine as one isolated system and the rotor as another isolated system. In its simplest terms, torque is the force required to move mass in a circular motion. Torque is caused by the engine providing power to the rotor shaft which moves the mass of the blades. The torque is the interaction of the stationary engine trying to move the stationary rotor blades in a circular motion. If you disconnect the engine from the rotor (for instance via a clutch), you eliminate the torque. The rotor is allowed to spin freely.
Tip jets remove the torque being supplied by the engine via the shaft because the engine is no longer providing power to the shaft. The reactive force of the jets is moving the mass of the isolated system of the rotor. The rotors mass is being moved without the need to receive power input from another outside system moving it in a circular motion.

This is true even with tip-jet rotors driven by air compressed by an engine and blown up the rotor shaft, BTW.  Germany flew at least one such helicopter during WWII.

@ZeissIkon I think you just described a  lawn-sprinkler  :-) .

@CarlWitthoft Never seen a lawn sprinkler with an internal engine pumping ambient water, but I get your drift...  ;)

Think of 2 scenarios: in one you are holding a rocket shaped projectile that is inert and you throw this projectile using your arm. In the second scenario you hold a real rocket, which is then launched.
In the first scenario you throw the projectile, and you have to counter the twisting motion of your arm because your arm is imparting a force. In the second scenario you don't have to take any action because the rocket does the work of moving the projectile instead of your arm.
A regular helicopter is like the first scenario, the engine pushes on the rotor, so the rotors push back. A tip jet is like the second scenario as the tips push themselves.

Ejection of the tipjet exhaust streams in different directions creates a reactive torque on the rotor. This causes the rotor to spin up until aerodynamic drag exactly opposes the jet reaction. So in a way you can say that tipjet helicopters cancel the rotor torque through aerodynamic drag.
But no torque is applied to the rotor through the rotor hub. Its bearings may create a tiny amount through friction, but that is negligible.


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What is the maximum G load a 747 can withstand during an emergency course reversal?
In an emergency course reversal, passenger safety first priority, to avoid say, a column of ash from a new volcano, what it the most G a 747 can withstand with an average passenger complement?

Related : https://aviation.stackexchange.com/q/8073/679

"Withstand" as in, before you break the wing spar or some other necessary component?  That all depends on the fatigue history of the aircraft and its exact gross weight. Unless you're pulling hard to avoid a SAM, nobody wants to go that far beyond the operating limitations of the flight manual.  I suspect that 60 degrees, which is 2 G's, is as much as anybody would really use.  But I'll defer to @Terry for the actual 747 driver's answer!

Also, once you leave level flight, you're sorta guessing at your G-loading. Level, G-loading maps to bank angle, although not (at all) in a linear way.  With a descent - the quickest way to make a 180, assuming you have terrain clearance - you can bank quite a bit & maintain a low G-load if you're willing to accept the lost altitude & gained speed. But without a G-meter (not typically found in airliners!) or a highly calibrated seat-of-the-pants, you don't KNOW how much G you're pulling. You can estimate, but you don't know -- unless you regularly pull 2, 2.5, 3, etc outside of airline flying.

@RalphJ What is the exact process of calibrating the seat of your pants?  :P

Possible duplicate of What does it take to turn a 747 around 180 degrees?

I disagree with the duplicate question. This question asks about limit loads and ultimate loads, the earlier question asked for a turning radius.

It depends on how you define :withstand". China Airlines flight 006 experienced vertical load factors of up to 5.1 g on 19 February 1985. The aircraft could be landed safely and there were no fatalities, but there was considerable damage:
Image source
From the NTSB incident report:

The wings were bent or set permanently 2 to 3 inches upward at the wingtips; however, the set was within the manufacturer's allowable tolerances. The left aileron's upper surface panel was broken and the trailing edge wedge was cracked in several places.

The maximum load factor an aircraft can be subjected to is a function of time. Two cases are determined for civil aircraft:

Limit load factor. For transport aircraft weighing more than 50,000 lb
(22,680 kg) this load factor is equal to 2.5, while for lighter aircraft it is a function of the weight.
Ultimate load factor = 1.5 times limit load factor, is the higher of the gust and the manoeuvre load factor.

The load factors are determined in accordance with the airworthiness regulations 14 CFR part 23.341 and 14 CFR Part 25.341. Damage tolerance of the airframe and the consequences of metal fatigue are stated in 14 CFR part 25.571.
The B747SP of the incident is an aeroplane that was designed and constructed in the 60s/70s, before Computer Aided Design and engineering were wide-spread, and the structures were designed with analytical mathematics and knowledge from experience, then tested for limit loads and ultimate loads. The more the design stresses can be modelled on a computer screen, the closer the wing ultimate load can be to 150% of limit load. Older aeroplanes did not have these modelling tools, and wings could end up to be stronger and heavier than they needed to be. Something that everybody applauds, but nobody wants to pay for with a higher ticket price.
A video of the B777 shows how the static testing for ultimate load is done: an actual wing is bent until it breaks. It is not a test of wing flex, it is a test of static strength.

The particular 747 of the incident had a wing designed for an MTOW of 378,000 kg, while actual MTOW of the 747SP was 320,000 kg: an extra load factor of 1.18. Fuel in the wing tanks provides extra bending relief, not for the ailerons though..

Civil aircraft certification requirements for airliners demand normal operations be possible up to 2.5g and down to -1g in clean configuration up to design manoeuvring speed, reducing above that speed. Googling EASA CS25 should show this for European-certified aircraft. The same design requirements furthermore specify that the structure must withstand loads in excess of these, but I am not quite sure as to the actual factors.
There have been accidents where design operational loads were exceeded which still ended with a safe landing.

My question was right inline with the picture of the damaged aircraft. If the turn does not cause the craft to immediately break but allows a landing and saves everyone's life that is the G loading I was asking about.

In clean configuration, as has already been said, it's +2.5 / -1g, this is called limit load. Then you add on a 50% factor to yield the 'proof load',  or ultimate fail load, which is proven in destructive testing.
But it's important to remember though, bits break by force, not G. G is just acceleration. So you have to multiply it by the aircraft weight to yield the shear force that breaks the wing root, spar, or whatever. That's why the limit load is applicable at Max Take Off weight. And also why a glider or aerobatic aeroplane can pull more G, because multiplied by the mass, the ultimate force applied to the components is lower.

Welcome to AV.SE! Note that the best answers would be ones that add information not previously covered.


text:
Is it allowed to wear polarized sunglasses in cockpit?

Is it true that Pilots are not allowed to wear polarized sunglasses?
What is the worst thing that can happen if wearing polarized
sunglasses in cockpit?

Asking several questions at once is not a good fit for this site. The first two are related and could be kept together, but the third is mostly unrelated and should not be here (and recommendation questions are generally not very good fit on SE).

this document was already linked to this related question. It seems to provide the answer.

Hello juni-j, welcome to Aviation.SE. I agree with Jan Hudec's comments.  Here my slightly tongue-in-cheek answers: 1) no that is not true, 2) you can die, although that may or may not be related to the sunglasses, 3) see this question as well.

@JanHudec: I agree this is a duplicate, but for anyone seeking advice on polarized sunglasses, this question will be much easier to find. I, therefore, prefer to vote for keeping it open.

@PeterKämpf, well, the point of duplicate is that the question stays there for Google to find and link to the answers of the existing one. But I don't actually think this is a duplicate. I was just linking to the resource, that was linked there already and that provides the information necessary here.

@JanHudec: Well, the best sites keep the number of clicks until you reach a satisfying answer as low as possible. Your answer is certainly helping more than some link.

This FAA document describes considerations for choosing sunglasses for pilots.
Since the document concludes, that

Polarized sunglasses are not recommended

I presume there is no rule that would explicitly forbid it. However there is always the “operate aircraft careless and reckless manner” paragraph and if you badly screwed up while wearing such sunglasses and there was grounded belief that some of the disadvantages of such sunglasses contributed to the incident, you could be charged with that.
The document quotes following reasons why they are not recommended:

may reduce or eliminate visibility of instruments with polarization-based anti-glare filters,
may reduce or eliminate visibility of LCD instruments (LCDs emit polarized light by design),
may interfere with visibility through an aircraft windscreen by enhancing striations in laminated materials,
may mask the sparkle of light that reflects off shiny surfaces such as another aircraft’s wing or windscreen, which can reduce the time a pilot has to react in a “see-and-avoid” traffic situation.

Even if your plane does not have any instruments with polarization filters and no issues with striations in laminated windshield, filtering reflections from other aircraft is definitely not what you want.
Note that in most other situations, filtering reflections (from water, cars, metal roofs etc.) is desirable and is why polarized glasses exist, because reflections from close objects can be blinding. But in aircraft you are far from the sources of reflection, so the risk of blinding reflection is low, while the reflections can alert you to presence of other aircraft that might otherwise be hard to spot when looking towards the sun.


text:
Who is responsible for getting approval of cabin layout?
There are many aircrafts. There are many layouts. Even same aircraft model can have many layouts. Emirates offer in-flight shower while other airlines do not. Toilets locations may differ from different airlines. Seat pitches can be widely different for competing budget airlines etc.
Who is responsible for getting all these layouts certified? Is there any guidelines or regulations about it?
Edit: there are aircrafts in every continent I know of. Any jurisdiction is fine. Best if you can compare between their differences. Just general idea of your familiar is good enough.

sorry, but as usual, which legislation? e.g., FAA and EASA might have different criteria

Yeah sorry but any jurisdiction is fine. Just want some general idea. If you can post about their differences it's even better :)

we tend to ask to restrict the jurisdiction because otherwise it might end up being "too broad". I'll wait for the first answers to come in, but in the meanwhile please take this into consideration.

Thanks for your comment. While I expect general rules, I think FAA jurisdiction answer will come first as more users are familiar with that rules.

I can answer for the FAA as that is the jurisdiction I am in and familiar with. The FAA (and I assume the other similar organizations) have a variety of guide lines for airplane interiors and its generally on the owner/operator to get them certified. However manufacturers may elect to get an interior configuration certified so that they can sell complete aircraft. As for regulations there are plenty of them, you may want to check this out as well as this and also this. The FAA generally looks at evactuation times (how long it takes every one to get out of the plane in the event of a crash) as well as certain aspects of the seats and restraints. Generally speaking they also look at the materials for their flamability.
One of the biggest interior policies of recent years was the move to "16G Seats" over the older seats. However as long as the seat is an approved 16G seat it can be used.
This is a nice summary of some of the research the FAA has done on cabin safety and its components.
As far as I know the FAA will let you submit just about any layout as long as it passes their flame, evac, and safety regulations. With the popularization of large private planes interior options are pretty much limitless.
On larger planes there are some things that may be fixed like the bathroom and galley since that requires plumbing and electric to be run but its more than likely they can be moved if requested.
There have even been talks of standing room only sections of airplanes but the regulators put a hard no to that as of now.


text:
Who has right of way on the ground?
In the air, concept of right of way does exist.
Does it also exist for ground operation as well? Possible conflict might come from where taxi ways intersect each other. Do pilots have to agree with each other who goes first or ground controllers do this for them?

At a controlled airport, ground maneuvering, taxi routing and sequencing, etc., will be assigned to you by ground controllers after you make contact with them and enter the controlled areas of the field.  Even here the rules below will apply when aircraft are maneuvering in non-controlled areas of the field e.g. parking aprons, hangar spurs, refueling areas, etc.
Pilots are generally courteous and conscientious people and will usually try to be helpful to both parties.
At a uncontrolled airport or an uncontrolled area of a controlled field, the following right of way rules are going to apply to maneuvering on the ground:

When two aircraft are approaching head on, or approximately so, each shall stop or where practicable alter its course to the right so as to keep well clear.
When two aircraft are on a converging course, the one which has the other on its right shall give way.
An aircraft which is being overtaken by another aircraft shall have the right-of-way and the overtaking aircraft shall keep well clear of the other aircraft.
An aircraft taxiing on the manoeuvring area shall stop and hold at all runway-holding positions unless an explicit clearance to enter or cross the runway has been issued by the aerodrome control tower.
Emergency vehicles proceeding to the assistance of an aircraft in distress shall be afforded priority over all other surface movement traffic.

Source: EASA (pdf pages 53-54)

Should not be to difficult to remember, that's the same rules as a drivers license...


text:
What is (or was) the "international frequency"?
I have recently read a book about Douglas BADER. This pilot has lost his legs (because of accident in 1931) but after (thanks to his single-mindedness) he takes up the "broomstick" again and became a ace with ~30 victory...
After he is shot and captured by the enemy: the Germans. Germans contact the UK in the "International frequency" to send prostheses. The Germans propose a deal but the RAF drops it during a bombing raid with 11 messerschmitt shot in the process.(at the same time)
What information are available about this frequency? (name, usage, frequency).
Have you question about this story?
Bonus :

It would be helpful if you could provide the source of that story

the page on the book?

So what do you want to know? What is the frequency? Who invent the frequency? Which side use this frequency? Etc. please state your question clearly.

@L'aviateur: Which book is that?

This is about HISTORY, not aviation.  That said, any shortwave news broadcast would be monitored in Great Britain, so putting the request on the news program would be sufficient.

it's not nice to edit and delete a lot of sentence and additional information

Your question need some editing. In english double punctuations ("?", ":", ";",) need space AFTER and not before, paragraphs must begin with new line. Your question could be simplified as "I read somewhere that during WWII Germans contacted UK on international frequency in order to [...]" followed by your question.

You can change the ponctuation if you want i have not enderstand

The international distress frequency has been 500 kHz, since 1908.
Copious details are at https://en.wikipedia.org/wiki/500_kHz.
During the war, this frequency was used for reporting distress and for monitoring distress, by the Germans and the British.  It was also used before and after the war for this purpose, by many countries, by aviators and mariners and others.

Is The communication  possible between uk and germans during the war on this frequency?


text:
Does F-35 flight stick have a trackball?
There is a trackball-looking thing on the side of F-35's side stick.
What is this? Is this actually a trackball?

There is also another round looking "button", although a bit different from the first one, on the lower back of the stick:

(The images are from here)

Looks very similar to the button low on the left side of the stick.  My guess is it's just another button, but I can't find any public documentation on the F-35 HOTAS controls.

@ErinAnne You can see in the pictures that the red button on the front has a conventional cylindrical cap like older generations of flight sticks, why would they choose a different cap design just for those two buttons? so I doubt it's just a button ... (and the one on the back isn't very clearly visible, it could be a hat switch)

The red one is likely the Weapon Release.  It isn't uncommon for other buttons on the stick not to match that; take a look at the A-10, F-22, and F-16 sticks to compare.

You could always send off for a copy of Essex Industries' manual for their side-stick.

M. Linux, why did you edit to remove the second image?  It was helpful, I'd suggest adding it back, because most people aren't going to click on the "from 'here'" link and thus will never see it--  thnx

quiet flyer, I removed that one to avoid confusion, because it seemed a little bit different from the side button.

quiet flyer, I included the second image again, with some clarification.

PS, a bit late to mention, but wouldn't a very small trackball be difficult to manipulate with a gloved hand/ finger?

quiet flyer, You could cut the glove's finger tips; and I actually saw some pictures of US fighter pilots wear such gloves as part of their flight suit.

quiet flyer, For example this: https://i.ytimg.com/vi/_6p-v5Nky7U/maxresdefault.jpg

That appears to be a button, not a trackball.
From pg. 17 in a presentation, Active Stick & Throttle for F-35 - Joseph Krumenacker - NAVAIR Flight Controls / JSF Vehicle Systems - 16 October 2008, found here:
It is used to engage/disengage stick sensitivity in hover. Inadvertent movement of the stick would disengage the altitude hold.
Engaging that S-5 button increases the force to needed to 'disengage'.

solution was a pilot-engageable “gripper” mode, in
which an altitude-hold augmentation could be
quickly engaged and disengaged
– with gripper engaged, longitudinal stick breakout
force is significantly increased to prevent
inadvertent disengagement
Pros

Hover stick force is “significantly higher” and provides pilot direct tactile feedback and
confirmation that the flight control system is in control of height axes
Push through or paddle off to begin vertical landing

Cons

Remembering to select height hold
More buttons required


text:
Why is the Concorde, and not other aircraft, getting this fog/condensation, over the wing, at *takeoff*?
Several pictures of the Concorde taking off, show a cloud of water droplets (fog) above the wings.  Like this:

I assume the fog is created due to low pressure over the wings. But, doesn't the size location and visible turbulence of this pattern suggest that the wing is stalled?  It certainly doesn't look like laminar flow.
I don't recall seeing this on other aircraft at takeoff.
What's going on?
Is it unique to the Concorde?
Is it exacerbated by ground effect?

This Wikia entry says:

...the undercarriage had to be unusually strong. This was due to the unusual loadings due to the high angle of attack that Concorde needed to take-off due to its delta-wing.

The "high angle of attack" would support my guess that the upper wing is stalled?
I could understand a stall if the aircraft was landing, but these seem to be near stall during takeoff?

This is by no means limited to the Concorde: https://c2.staticflickr.com/8/7170/6777607687_392329226c_b.jpg

@JonStory, Yes, but on other aircraft it only occurs when the wing is nearing full stall -- much more often during landings than in takeoffs.

Not really - an airliner lands at or above Vref, which is ~1.3x stall speed. Takeoff (rotation) typically happens at a slower speed, below V2 - and V2 itself is only ~1.2x stall speed. That photo I posted is a 747 on takeoff, not landing.

You're correct that the condensation is due to low pressure, but the wing is not stalled. The highly swept delta wing of the Concorde created lift be what is called vortex lift. From my answer in that question:

In the case of wings having sharp, highly swept leading edges like delta wings, the leading-edge separation vortex phenomenon occurs at subsonic speeds. However, the separation does not destroy the lift as in the case of low sweep wings; instead, it forms two vortices which are (nearly) parallel to the wing edges.

The centre of the vortex is a low pressure region, where condensation forms. In this figure, you can see the vortex formation in a model of Concorde.

Flow around Concorde in a landing Configuration by Henri Werlé, ONERA, image from efluids.com
A side view of the same thing:

Flow around Concorde in a landing Configuration* by Henri Werlé, ONERA, image from efluids.com

So, basically, the aircraft is still producing lift; only the mechanism is different.
This kind of lift production is quite common in case of highly swept wings. The vortex formation is also found in a number of other cases like chines, leading edge extensions (like this F-18), etc.

Flow visualization over a 1/48-scale model of an F-18 aircraft inside a water tunnel at the Flow Visualization Facility from NASA's Dryden Flight Research Center. Image from wikimedia commons

You're right to assume low pressure on top of the wing as cause of the condensation. As far as location and turbulence, this would probably have to do with something called "Span Wise Flow" in which air flowing over a wing doesn't just flow straight back, but tends to drive outward towards the wingtips and spill over the edge (a reason for 'winglets').


text:
What does it mean "two plane thrust vectoring nozzle"?
It has been said that only Sukhoi 35 has the "two plane TVN" others like F 22 and Su 30MKI (produced by India under license at Hindustan Aeronautics Limited)  have "one plane TVN".So what the difference ?

Substitute "axis" for "plane" and the meaning may become clearer.

Two planes connected by one nozzle.

This statement is using "plane" in the mathematical-geometric sense, which is of course very confusing when we talk about a part of a "plane" in the "flying machine" sense.
So, a "one-plane" thrust vectoring nozzle can only move up and down or left and right (typically up and down). So, this gives you pitch control using the thrust, without requiring airflow over the elevators. This is sometimes called "1D" thrust-vectoring, but it is also (confusingly) sometimes called "2D" thrust-vectoring (see the last paragraph).
A "two-plane" thrust vectoring nozzle can move up and down and left and right. So, this gives you yaw control without using the rudder in addition to pitch control. This is sometimes called "2D" thrust-vectoring, but it is also (confusingly) sometimes called "3D" thrust-vectoring (see the last paragraph).
In a two-engine aircraft, in both cases, you can add another "virtual" axis by having independent vectoring of the two nozzles, e.g. one up and one down, which gives you roll control. That is why, for two-engined aircraft, we sometimes talk about "2D" and "3D" even if the individual nozzles only can move on one or two dimensions.

For those who don't know
"thrust vectoring, also thrust vector control or TVC, is the ability of an aircraft, rocket, or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to control the attitude or angular velocity of the vehicle.
In rocketry and ballistic missiles that fly outside the atmosphere, aerodynamic control surfaces are ineffective, so thrust vectoring is the primary means of attitude control.
For aircraft, the method was originally envisaged to provide upward vertical thrust as a means to give aircraft vertical (VTOL) or short (STOL) takeoff and landing ability. Subsequently, it was realized that using vectored thrust in combat situations enabled aircraft to perform various maneuvers not available to conventional-engined planes. To perform turns, aircraft that use no thrust vectoring must rely on aerodynamic control surfaces only, such as ailerons or elevator; craft with vectoring must still use control surfaces, but to a lesser extent."
-Methods of thrust vectoring
-Type I
-Nozzles whose baseframe mechanically is rotated before the geometrical throat.
-Type II
-Nozzles whose baseframe is mechanically rotated at the geometrical throat.
-Type III
Nozzles whose baseframe is not rotated. Rather, the addition of mechanical deflection post-exit vanes or paddles enables jet deflection.
-Type IV
"Jet deflection through counter-flowing or co-flowing (by shock-vector control or throat shifting) auxiliary jet streams. Fluid-based jet deflection using secondary fluidic injection.
Additional type
Nozzles whose upstream exhaust duct consists of wedge-shaped segments which rotate relative to each other about the duct centreline.
The Lockheed Martin F-35 Lightning II while using a conventional afterburning turbofan (Pratt & Whitney F135) to facilitate supersonic operation, the F-35B variant, developed for joint usage by the US Marine Corps, Royal Air Force, Royal Navy, and Italian Navy, also incorporates a vertically mounted, low-pressure shaft-driven remote fan, which is driven through a clutch during landing from the engine. Both the exhaust from this fan and the main engine's fan are deflected by thrust vectoring nozzles, to provide the appropriate combination of lift and propulsive thrust. It is not conceived for enhanced maneuverability in combat, only for VTOL operation, and the F-35A and F-35C do not use thrust vectoring at all.
The Sukhoi Su-30MKI, produced by India under license at Hindustan Aeronautics Limited, is in active service with the Indian Air Force. The TVC makes the aircraft highly maneuverable, capable of near-zero airspeed at high angles of attack without stalling, and dynamic aerobatics at low speeds. The Su-30MKI is powered by two Al-31FP afterburning turbofans. The TVC nozzles of the MKI are mounted 32 degrees outward to longitudinal engine axis (i.e. in the horizontal plane) and can be deflected ±15 degrees in the vertical plane. This produces a corkscrew effect, greatly enhancing the turning capability of the aircraft"
Vectoring in two dimensions
 -McDonnell Douglas F-15 STOL/MTD (experimental)
-Lockheed Martin F-22 Raptor (pitch and roll)
-Chengdu J-20 (with WS-10B or AL-31FM2 engine, pitch and roll)
-Sukhoi Su-30MKM (pitch and roll)
-Sukhoi Su-30MKI (pitch and roll)
-Sukhoi Su-30MKA (pitch and roll)
-Sukhoi Su-30SM (pitch and roll)
-Sukhoi Su-35S (pitch and roll)
-Sukhoi Su-57 (pitch and roll)
-McDonnell Douglas X-36 (yaw only)[23]
-Me 163 B experimentally used a rocket steering paddle for the yaw axis
It is thrust vectoring in one,two or three dimension(so in 1/2/3 axis)
Source: https://en.wikipedia.org/wiki/Thrust_vectoring

Maybe I am stupid, but I fail to see an answer to the question being asked: what is the difference one-plane and two-plane thrust vectoring?

This answer appears to be a copy/paste from Wiki providing background on what thrust vectoring is. While informative, it does nothing to provide an answer to "What is 2-plane thrust vectoring?". The last, bolded sentence makes an attempt to actually answer the question, but it starts with "Maybe", which is hardly the fact-based, authoritative type answer we look for at SE.

Also, any copy-paste should be block quoted so we can see what is (and isn't) original content.


text:
What are the pros and cons of high service ceilings for fighter jets?
What are the pros and cons of high service ceilings for fighter jets?
Can they bypass radars and attack effectively at high ceilings?

It's easy to convert potential energy into kinetic energy in a matter of seconds. The reverse is not so easy. Also, if the ceiling is lower than the enemy's, it's hard to intercept him.

Do you have a particular role in mind, such as interceptor, dogfighter or attack fighter?

Are you inquiring about the tactical pros and cons of being at a higher current altitude? Or, do you want to know more about an aircraft’s ability to fly to a higher altitude if necessary. Since a higher service ceiling for cruise flight may not be the altitude for their military mission operational or combat altitude.

If your question is about advantages and disadvantages of the high ceiling:
Advantages:
-For military aircraft, reaching a high ceiling gives a tactical advantage in air combat and makes it possible to escape from surface-to-air defense . For civil aircraft, it is above all a question of achieving the best efficiency of the engines or of being able to take advantage of the air currents . For both civilian and military helicopters a relatively high ceiling allows intervention in mountainous regions.
-During the Cold War the race for the altitude record was part of the propaganda war between the two blocks. It is however necessary to distinguish the maximum altitude reached during records, not supported, and the operational ceiling of an aircraft, given for standard mission (military) or operating (civil) conditions, and which is the maximum altitude to which the plane can stay in a sustained manner. For example, the absolute altitude record for a conventional jet plane, held by the Ye-266M (one of the prototypes of the MiG-25 ) is 37,650  m , but this same plane has a ceiling of "only" 24 400  m . In the same vein, the Lockheed NF-104A, a demilitarized version of the F-104A Starfighter used by NASA to train the pilots of X-15 , could climb to altitudes higher than 36 600 meters thanks to its additional rocket engine, but its actual ceiling was only about 15,000  m .
Research continues to push the limits reached during this period, with aircraft such as the X-43 and its supersonic ramjet .
Disadvantages:
but nowadays, missiles have evolved and fly faster, higher .... now it's not a race for altitude.
now you have to be stealthy, have good self-protection systems.
it's time for the hypersonic era!
"The first Russian Avangard hypersonic missile regiment, capable of spinning at more than 33,000 km / h and piercing any existing missile shield, has officially entered service."china have same hypersonic missiles